Honestly, a differential on a human powered vehicle is a solution looking for a problem...

Think about it -- the rear drive wheel on a delta trike or quad sits just 16 inches to the left or right of the centerline at most. Do you really think that makes a huge difference? I doubt it -- otherwise if there was a problem don't you think all the major manufacturers of trikes would have addressed it by now???

Imho a waste of money and a needless addition of weight.

My zwei pfennigs...